Liquid-cooled transformer winding

ABSTRACT

The invention relates to a liquid-cooled transformer winding, preferably a disc winding, of the type in which the coolant is led through cooling tubes which are arranged in the winding simultaneously with the manufacture of the winding. The cooling tubes are arranged in only some of the winding discs, called cooling discs, and these cooling discs are preferably evenly distributed within the winding.

United States Patent Tjernsteom Apr. 15, 1975 [54] LIQUID-COOLED TRANSFORMER L T/L096 10/1923 Brand 336/62 WINDING 3.467.93l 9/1969 Dutton 336/187 x 3.503.026 3/1970 Gciscl et a1. 11 336/62 {75] Inventor: Ove j st Luovikut Sweden 3.728.655 4/1975 Reinkc 336/62 [73] Asslgnee. Allmanna Svenska Elektnska FOREIGN PATENTS OR APPLICATIONS Aktlebolaget, Vasteras Sweden 180000 7/1962 Sweden 336/62 [22] Filed: Sept. 5, 1974 655.964 8/1963 ltaly .4 336/187 1.049.007 9/1955 Germany 336/62 Appl. N0.: 503,442

Related US. Application Data Continuation of Set. No 403,491, Oct. 4. abandoned.

Foreign Application Priority Data Oct. 5 1972 Sweden 12825/72 0.8. Ci 336/62; 336/187 Int. Cl. H0" 27/10; H01f 27/28 Field of Search 336/55. 60, 62, 186, 187;

References Cited UNITED STATES PATENTS 10/1921 Stephens 336/62 X [57] ABSTRACT The invention relates to a liquid-cooled transformer winding, preferably a disc winding. of the type in which the coolant is led through cooling tubes which are arranged in the winding simultaneously with the manufacture of the winding. The cooling tubes are arranged in only some of the winding discs, called cooling discs, and these cooling discs are preferably evenly distributed within the winding.

1 Claim, 3 Drawing Figures LIQI'ID'COOLED TRANSFORMER WINDING has This is a continuation of application Serial .\'o. 403.4%. filed ()ct. -l. I973. now abandoned.

BACKGROUND OF THE INYEXTIOX 1. Field of the Invention The invention relates to direct liquid-cooling of transformer windings.

I. The Prior Art In direct liquidcooling of transformer windings the required length of the cooling tubes will be very large if the cooling tube is to follow the conductor for its entire length. This applies particularly to highwoltage windings. where the number ofturns can be very great. in many cases over a thousand.

Furthermore. it is unrealistic to ha\e only one input and one output because of the great length of the cooling coil which may be several thousand metres long. It is then necessary to ha\e either a very high pump pressure to feed through a sufficient amount of liquid. or a wry large cooling tube area. and this causes a disastrous decrease in the fill factor of the winding. A division into a number of preferably parallel cooling circuits is therefore necessary in practice. In this connection the problem arises of being able to arrange inlets and outlets for the coolant in a simple and practical manner. while at the same time the length of the cooling tube must be limited. both in view of the cost of the cooling tubes and in iew of the fill factor of the wind- SL'MMARY OF THE INVENTION The present invention aims at a solution to the above problem with direct liquid-cooling of transformer wind ings. preferably disc windings of the type in which the coolant is led through cooling tubes which are arranged in the winding simultaneously with the manufacture of the winding.

The particular characteristics of the invention are that a disc winding is provided with cooling tubes which are arranged in the windings during the manufacture thereof. the cooling tubes being arranged only in some of the winding discs. these cooling discs being evenly distributed within the winding. Furthermore. the invention contemplates a continuous member forming apart of the disc. parts of this member in some of the discs being hollow and pro\iding a cooling passage while those in other discs are solid.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings FIG. I shows a vertical section through part of the winding. FIG. 2 shows part ofthe cooling conductor and FIG. 3 shows a crosssection through two discs. one disc being manufactured.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The conductor bundle which is used in the manufacture of the winding in the example of the invention which will now be described have five solid conductor parts a. l c. 1/ and e and a cooling tube f. Of these. a. h and c are normal copper conductors. each one being drawn from a coil in the manufacture of the winding. whereas the parts d and c and the cooling tube f are joined to each other and connected to form a cooling conductor which is manufactured beforehand. As is clear from FIG. 2. the cooling conductor comprises a through part d of the same type as u. h and and also part t' which. together with the four previously mentioned parts 0.1 c and d. is included in the discs which lack cooling. In those discs in which cooling is arranged part c is replaced by cooling tube f. and at the beginning and end ofthe cooling tube part 4' and cooling tube lure joined by means of soldering at I. The length of the cooling tubej'and the conductor part 4' and the lo cation of the joints I are calculated beforehand based on information about the diameter of the winding. the number ofturns per disc. and so on. In the manufacture of the cooling conductor inlets 2 are arranged at both ends of the cooling tube and outlet 3 is positioned in the centre of the cooling tube. The cooling conductor is wound up on its own coil and is wound on together with parts a. h and t.

The winding is assumed to be manufactured in known manner with the discs wound alternately from the inside outwards and from the outside inwards. respectively. When changing from one disc to another permutation of the conductor parts takes place so that the outermost part in one disc will be the innermost part in the next disc. It is thus clear from FIGS. l and 3 that in disc A the cooling conductor with its cooling tubeflies farthest in. but after four turns. when the disc A is completed. permutation takes place in connection with the transition front disc A to disc B so that in this the cooling conductor with the cooling tube f has an outermost position. When disc B is finished the transition to disc C is made with permutation of the conductors so that discs A and C will be the same.

With reference to FIG. 3. the cooling conductor in disc A according to FIG. 2 is made in such a way that during the part of the innermost turn when the permutation from the immediately preceding turn (not shown in the Figurel is finished. the cooling tube lies farthest in. At this very part the cooling conductor changes from the conductor part t to the cooling tube f with an inlet 2. seen at the top or bottom of FIG. 2. The inlet 2 on the cooling tube fwill thus be located on the inside of the winding. After four turns the disc A is completed and the permutation into disc B. starting with the conductor part a. begins. After almost another turn the permutation is finished and the cooling tubefis farthest out. Then the outlet 3 will be accessible and will therefore be placed on the outside of the winding. After another four turns the disc B is finished and the conductor bundle has proceeded and formed the innermost turn in disc C. Again the cooling tube is at the inmost position with the other inlet 2 on the inside of the winding.

The part of the winding disc where the cooling tube is accessible. either on the inside of the winding. as in disc A. or on the outside of the winding as in disc B. is a few decimetres in size. depending on the diameter of the winding and on the permutation being carried out evenly distributed along the entire turn or only part thereof. If the permutation is evenly distributed said distance. with five parallel conductor parts. as in the case shown. will be one fifth of the circumference. If the average diameter of the winding is L5 metre said distance will be about I metre. In that case the arrangement according to FIG. 2 is possible. i.e. placing a T- tube on the cooling tube and providing a common outlet for two discs or providing separate inlets and outlets that is connections to the outside for each disc. The

term cooling discs-- as used herein is intended to designate discs such as those shown which have cooling tubes forming part of the windings thereot.

As the conductor part c ceases when the cooling tube starts. the cooling tube ma work as conductor part if it consists of electric-all conducting material. 'lhis will tend to the area of the total conductor area being sonicwhat smaller in the cooling discs. but on the other hand the cooling is better there.

A transformer winding manufactured according to the example shown will thus have a number of cooling discs prel'erabl tairl e\enl distributed in the winding and suitabl arranged two and two. as illustrated in FIG. 1. The inlets of the cooling tubes are arranged on the inside of the winding and the outlets on the outside or \ice \ersa. lnlets as well as outlets are connected to common feeder tubes at the sides of the winding. thus making the cooling tubes parallel-connected Because of the great flexibility with regard to the number and positioning of the cooling discs. there are \irtuall unlimited possibilities of arranging cooling discs in the winding. thus providing the desired cooling every here in the winding. It is possible. for example. to put in an increasing number of cooling discs counting from below and upwards towards the winding top where the highest temperature pre\ails.

I claim I. Liquid-cooled transformer winding of the disc t \pe. in which a plurality of adjacent discs are each formed of a plurality of parallel conductor parts of the same cross-sectional width wound spiral! in a pluralit olturns. a majority of said conductor parts being solid. at least one of the conductor parts being hollow and comprising a tube for a cooling medium. said tube forming at least a portion of the innermost coil of a first of said discs. being transposed at the outside of the winding to form at least a portion of the outer coil of the second adjacent disc and being further transposed at the inside of such second. adjacent disc to form at least a portion of the inner coil of the third. nest adjacent disc. said tube portions having openings thereinto for ingress and egress of cooling fluid from outside the winding. 

1. Liquid-cooled transformer winding of the disc type, in which a plurality of adjacent discs are each formed of a plurality of parallel conductor parts of the same cross-sectional width wound spirally in a plurality of turns, a majority of said conductor parts being solid, at least one of the conductor parts being hollow and comprising a tube for a cooling medium, said tube forming at least a portion of the innermost coil of a first of said discs, being transposed at the outside of the winding to form at least a portion of the outer coil of the second adjacent disc and being further transposed at the inside of such second, adjacent disc to form at least a portion of the inner coil of the third, next adjacent disc, said tube portions having openings thereinto for ingress and egress of cooling fluid from outside the winding. 